Every Mac user has noticed it; over time, your system slows down. This is particularly true in these days of constant security updates, as replacing operating system components not only increases file fragmentation, but also creates a more insidious problem—over time, the operating system itself ends up scattered all over your disk.
This, of course, doesn’t show up as fragmentation—after all, the files themselves are probably contiguous—but nevertheless, it takes your machine longer to start up, it takes programs longer to start, and it takes longer to get your work done. iDefrag solves these problems and more, by defragmenting and optimizing your Mac’s filesystem.

New in iDefrag 2Defragment individual filesSelect and defragment individual files without touching the rest of your disk.No bootable CD/DVD required!iDefrag no longer needs a bootable CD/DVD; instead, simply click Go and iDefrag reboots your machine into a special mode allowing you to defragment without using a separate boot disk.Improved performanceiDefrag 2 is the fastest version yet, including numerous performance tweaks to speed up defragmentation.Improved user interfaceFor version 2, we’ve overhauled the user interface to reduce clutter and improved accessibility for disabled users.

System RequirementsMac OS X 10.6 or later (including Mountain Lion), Intel microprocessor, 1GB RAM. Supports internal and external disks. To defragment your boot volume, you need to boot from a different volume (except for on-line defragmentation feature) or reboot into a special mode.

iDefrag can only defragment HFS and HFS+ volumes (i.e. Mac disks). It will not defragment FAT or NTFS volumes; if you are using these for compatibility with Windows systems, please use a Windows-based defragmenter.